The organisers of the Open Championship have blamed hot weather rather than high ticket prices for a drop of almost 20,000 spectators from the last time the event was staged at Muirfield.

In 2002, a total of 160,595 attended the third major of the year in East Lothian. Last week, that figure fell to 142,036 with a standard walk-up price of £75 generally recognised as off-putting. That represented an increase of £5 from a year ago and £10 from 2011 at Royal St George's.

Before the Open started, the chairman of the R&A's championship committee, Jim McArthur, said: "We are expecting a total crowd of 160,000, and hoping for 170,000 over the week."

In defending the subsequent numbers, a spokesman for the Open said: "More than 142,000 people attended the Open this week.

"That is almost 90% of the figure in 2002 and we are pleased with this attendance. Advance ticket sales were very strong and we believe the extremely warm weather put off some of our pay-at-the-gate customers. That is perhaps why, unusually, we had a higher attendance on Sunday in cooler weather than we did on Friday which is normally the busiest day.

"The blend of a British winner of the Tour de France and Ashes cricket on television over the last few days may also have had an impact."

During practice days, when tickets were cheaper, the attendance figure was comparative to 11 years ago but it dropped sharply, by 25%, for the first round. In 2002, tickets for competitive days were less than half of this time around, at £35. Another crucial factor this year was the absence of discounted tickets for senior citizens.

Peter Dawson, the chief executive, and other senior R&A figures did not hold their standard post-Open press conference on Monday morning. No reason was given but the potential for bad publicity on account of attendance numbers, added to the scrutiny placed on the organisation for hosting the Open at clubs such as Muirfield, which has a male-only membership policy, cannot be ignored.

The Open generates anything between £50m and £100m for local economies, with money received by the R&A also reinvested at grassroots golfing levels. Those who made the cut at Muirfield collected prize money totalling £5,056,545. The winner, Phil Mickelson, collected £945,000 of that total.

The R&A has also stressed that juniors under 16 gain free entry to the Open. It has further defended pricing by stating: "The Open Championship offers excellent value in line with other world-class sporting events."